A Multi-City Investigation of Exposure to Diesel Exhaust in Multiple Commuting Modes Columbus OH, Austin TX, Boston MA, New York City, NY

The report documents that commuters in cars, buses, trains, and ferries are routinely exposed to high levels of diesel exhaust, with ultrafine particles (UFPs) serving as the most sensitive marker of fresh diesel emissions. Findings indicate that diesel soot dominates roadway particulate matter and that in-vehicle exposures are significantly higher than ambient outdoor air, particularly in 'pull' trains and highway tunnels. The study concludes that diesel particulate filters (DPFs) are highly effective at eliminating the soot plume behind vehicles, significantly improving air quality for following commuters and pedestrians.

• Commuters in cars experience their highest daily exposure to diesel particles during their trip to work, with mean ultrafine particle (UFP) exposures ranging from 4 to 8 times ambient outdoor levels and peak levels reaching 19 to 38 times ambient concentrations.
• Diesel particulate filters (DPFs) significantly reduce pollution; chase studies in New York City and Boston showed that DPF-equipped buses and sanitation trucks eliminate the diesel soot plume, whereas conventional buses leave concentrated trails of soot that permeate following cars and sidewalks.
• Commuter rail coaches are polluted by diesel exhaust, especially in 'pull' configurations where the locomotive is in front. In these cases, mean UFP exposures were 15-20 times outdoor air, compared to 3-5 times in 'push' trains where the locomotive is in the rear.
• Underground rail stations, specifically Boston's Back Bay Station, exhibit extreme pollution levels that penetrate passenger coaches when doors open. Peak concentrations at Back Bay reached averages of 1,225 ug/m3 for PM2.5 and 157 ug/m3 for black carbon.
• In-vehicle air quality in cars is heavily influenced by ventilation settings; exposures are highest with windows open and lowest when air conditioning or heat is used with the cabin air set to recirculate.
• Boston commuter ferries show very high short-term diesel smoke levels in passenger cabins, with mean peak exposures for particulate PAH reaching 117 times and black carbon 50 times the ambient outdoor air.
• Pedestrians on city sidewalks in Boston and Columbus are exposed to spikes of diesel exhaust as vehicles pass, with average peak exposures for UFPs ranging from 19 to 29 times outdoor ambient levels.
• Ultrafine particles (UFPs) are identified as the most sensitive indicator of fresh diesel exhaust across all transit modes, showing rapid fluctuations in response to diesel vehicle acceleration and presence.
• Diesel trucks are the primary source of particulate matter on highways; routes that ban large trucks are characterized by lower exposures to all four measured particle pollutants.
• Electrified subways in New York and Boston generally have low combustion-related pollution, though they exhibit elevated fine particles (PM2.5) likely due to non-combustion rail dust.
• The report estimates that diesel soot is responsible for approximately 21,000 premature deaths per year in the United States.

APA

Hill, L. B., & Gooch, J. (2010). A Multi-City Investigation of Exposure to Diesel Exhaust in Multiple Commuting Modes Columbus OH, Austin TX, Boston MA, New York City, NY. Clean Air Task Force. https://cdn.catf.us/wp-content/uploads/2019/02/21093812/CATF_Pub_Diesel_Exhaust_Exposure_Investigation.pdf

Chicago

Hill, L. Bruce, and James Gooch. A Multi-City Investigation of Exposure to Diesel Exhaust in Multiple Commuting Modes Columbus OH, Austin TX, Boston MA, New York City, NY. Clean Air Task Force, 2010. https://cdn.catf.us/wp-content/uploads/2019/02/21093812/CATF_Pub_Diesel_Exhaust_Exposure_Investigation.pdf.

Wikipedia

{{cite report |last1=Hill |first1=L. Bruce |last2=Gooch |first2=James |title=A Multi-City Investigation of Exposure to Diesel Exhaust in Multiple Commuting Modes Columbus OH, Austin TX, Boston MA, New York City, NY |publisher=Clean Air Task Force |date=1 April 2010 |url=https://cdn.catf.us/wp-content/uploads/2019/02/21093812/CATF_Pub_Diesel_Exhaust_Exposure_Investigation.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{hill2010multicity, author = {Hill, L. Bruce and Gooch, James}, title = {{A Multi-City Investigation of Exposure to Diesel Exhaust in Multiple Commuting Modes Columbus OH, Austin TX, Boston MA, New York City, NY}}, institution = {Clean Air Task Force}, year = {2010}, month = apr, url = {https://cdn.catf.us/wp-content/uploads/2019/02/21093812/CATF_Pub_Diesel_Exhaust_Exposure_Investigation.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }